<!DOCTYPE html>
<html>
<head>
	<meta charset="utf-8">
	<title></title>
	<style type="text/css">
		.class1 .class3 {/* 0,0,2,0  */
			color: orange;
		}
		.class1 .class2 {/* 0,0,2,0  */
			color: red;
		}
		.class3 { /* 0,0,1,0  */
			color: blue;
		}
	</style>
</head>
<body>
<div class="class1">
	<p class="class2 class3" >红色</p> 
	<!-- 与引入顺序没关系，取决于定义时的顺序 -->
</div>
</body>
</html>